Redeeming Knight

Whenever a creature is killed by RK increase its justice by one
( RK has {x} amount of {w} symbols in it's converted mana cost, {x} being equal to its justice )All black creatures get -{x} -{x} equal to RK justice count.RK can not be killed, put to a graveyard, removed from the battlefield by a black source.
RK's takes double damage from white sources
Rk's attack and defence is determined by its justice.
Darkness within - At the start of a phase if this creature has {0} Attack deal damage to all non-b